@media (max-width: 960px) {
  .site-nav { position: absolute; top: 72px; right: 20px; left: 20px; display: none; padding: 24px; border: 1px solid var(--line); background: var(--paper-light); box-shadow: 10px 12px 24px var(--shadow); }
  .site-nav[data-open="true"] { display: grid; }
  .site-nav .button { justify-self: start; }
  .menu-button { display: inline-flex; }
  .hero-grid, .diagnostic-grid, .roadmap-grid, .fit-grid, .evidence-grid { grid-template-columns: 1fr; }
  .hero-copy { order: 1; }
  .cover-stage { width: min(330px, 78vw); order: 2; }
  .diagnostic-art { display: none; }
  .method-steps { grid-template-columns: 1fr; margin-top: 20px; border-top: 0; border-left: 3px solid var(--ink); }
  .method-steps li { display: grid; grid-template-columns: 70px 1fr; padding: 0 0 28px 28px; }
  .method-steps span { margin: 0 0 0 -57px; }
  .method-steps h3 { margin: 5px 0 8px; }
  .model-grid { grid-template-columns: 1fr 1fr; }
  .model-grid article { min-height: 230px; }
  .model-grid article:nth-child(3) { border-left: 0; border-top: 1px solid rgba(255,255,255,0.28); }
  .model-grid article:nth-child(4) { border-top: 1px solid rgba(255,255,255,0.28); }
  .roadmap-grid > img { justify-self: center; }
  .final-mark { display: none; }
  .final-grid { grid-template-columns: 1fr; }
}

@media (max-width: 680px) {
  :root { --shell: min(100% - 28px, 1160px); }
  body { font-size: 16px; }
  h1 { font-size: clamp(2.7rem, 14vw, 4.4rem); }
  h2 { font-size: clamp(2.25rem, 11vw, 3.5rem); }
  .header-inner { min-height: 64px; }
  .site-nav { top: 64px; }
  .hero { padding-top: 46px; }
  .hero-grid { gap: 0; }
  .hero-copy { display: contents; }
  .hero-copy .eyebrow { order: 1; }
  .hero-copy h1 { order: 2; }
  .hero-lede { order: 3; }
  .cover-stage { width: min(245px, 72vw); order: 4; margin: 10px auto 46px; }
  .cover-stage figcaption { margin-top: 20px; }
  .hero-actions { order: 5; }
  .proof-strip { order: 6; }
  .boundary-note { order: 7; }
  .hero-actions { align-items: flex-start; flex-direction: column; }
  .hero-actions .button { width: 100%; }
  .proof-strip { display: grid; grid-template-columns: 1fr 1fr; }
  .cover-shadow { inset: 16px -12px -12px 16px; }
  .signal-list p { grid-template-columns: 44px 1fr; gap: 10px; }
  .pull-quote { padding-left: 18px; }
  .diagnostic-form fieldset { padding: 18px 12px; }
  .comparison { grid-template-columns: 1fr; }
  .comparison-side + .comparison-side { border-top: 1px solid var(--line); border-left: 0; }
  .model-grid { grid-template-columns: 1fr; }
  .model-grid article { min-height: auto; }
  .model-grid article + article { border-top: 1px solid rgba(255,255,255,0.28); border-left: 0; }
  .evidence-grid { gap: 20px; }
  .evidence-number { font-size: 7rem; }
  .footer-inner { flex-direction: column; }
  .sample-header-inner { min-height: 64px; }
  .sample-hero { padding: 45px 0; }
  .sample-hero-grid { grid-template-columns: 1fr 88px; gap: 22px; }
  .sample-hero h1 { font-size: clamp(2.4rem, 11vw, 3.3rem); }
  .book-sample { padding-top: 60px; padding-bottom: 70px; }
  .book-sample blockquote { margin: 34px 0; padding-left: 20px; }
  .sample-end-grid { grid-template-columns: 1fr; }
  .sample-end-actions .button { width: 100%; }
}